'acel' is an accelerator factor whose value can be configured in the Sonar settings page.
The default threshold for each metric can be also configured (for instance, 50 is the default response_for_class threshold).

Code (CODE)

Code = 0.15*DOC + 0.45*RULES + 0.40*DRYNESS

DOC = Documented API density

RULES = Rules compliance index

DRYNESS = 100 - Duplicated lines density

Test (TS)

Testing quality is based on coverage metric family (coverage, and test success).

Test = 0.80*COV + 0.20*SUC

COV = Code coverage

SUC = Unit Tests success density

Configuration

Every limit and every formula should be configure with administration view.
If you want to remove a metric just do,